Question About Solar Amps Being Displayed

solartechtown.com
solartechtown.com Solar Expert Posts: 29 ✭
in Solar Beginners Corner #1
Hi all,

I made a short clip about one concern I have about the new Morniningstar Prostar 30 charge controller I purchased here: click here (video)

( :D Check out my little ant farm in the power outlet that will meet their maker soon :grr )

Link to charge controller: ProStar 30
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  • mikeo
    mikeo Solar Expert Posts: 386 ✭✭✭
    #2
    Re: Question About Solar Amps Being Displayed
    about one concern
    You are correct that the charge controller will only supply what the battery and loads require up to the max amperage the panels can produce. Also your inverter should be hooked directly through a fuse to the battery and not to the load connections on the controller. The load connection is to supply a 12 volt load to a device that you would want to automatically disconnect when the battery drops to to to low a voltage. LVD and can reconnect when the battery gets sufficiently recharged. An inverter can draw much more current then the load terminals are rated for on this controller. If it is a very small inverter then it may work OK on the load outputs. Many inverters have their own LVD circuit to protect your batteries.
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  • solartechtown.com
    solartechtown.com Solar Expert Posts: 29 ✭
    #3
    Re: Question About Solar Amps Being Displayed
    mikeo wrote: »
    You are correct that the charge controller will only supply what the battery and loads require up to the max amperage the panels can produce. Also your inverter should be hooked directly through a fuse to the battery and not to the load connections on the controller. The load connection is to supply a 12 volt load to a device that you would want to automatically disconnect when the battery drops to to to low a voltage. LVD and can reconnect when the battery gets sufficiently recharged. An inverter can draw much more current then the load terminals are rated for on this controller. If it is a very small inverter then it may work OK on the load outputs. Many inverters have their own LVD circuit to protect your batteries.

    Oh really, I did not know that. So glad I made this video then, as before I purchased this charge controller, I did have the inverter hooked directly to the battery, however I did not have a fuse on it.

    Could you possibly link me to a fuse I could use in this system as I'm not sure where to start as far as picking the right "type" of fuse.

    My inverter is a 400W (2x 200W for each outlet) inverter, and I probably don't have anything I need to continue to supply 12V to, so I'll probably just disconnect the inverter from those terminals and hook them straight to the battery with a fuse.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,641 admin
    #4
    Re: Question About Solar Amps Being Displayed

    Also, what is your charging voltage set at? The meter was displaying around 13.9 volts and the battery Green LED was flashing--which appears to indicate that the battery is nearly fully charged (and in PWM mode--basically, throttling the current back to maintain the battery voltage at Float~13.7 volts or Bulk/Absorb around 14.4 volts for flooded cell batteries).

    I would double check the battery type settings--I would expect 14.4 volts if it was charging (and in PWM mode), or 13.7 if it was in float. 13.9 is a bit in between. :confused:

    Also, what gauge is the wire and how long of wire run from the charge controller to the battery bank. A small gauge wire/too long of run can also "trick" the charge controller into thinking the battery is at a higher voltage than it really is (voltage "drop" or increase in small gauge wire--Meter may read 14.4 volts, battery may be at 13.3 volts due to charging current flow).

    Another help would be to attach the "voltage sense leads" from the controller directly to the battery bank. The controller will be able to more accurately read the correct battery bank voltage.

    And as Mikeo says--unless this is a very small inverter (less than 100 watts ?), you would be better off connecting the inverter directly to the battery bank. Hmmm, I could not find the LVD maximum current rating in the manual???

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • solartechtown.com
    solartechtown.com Solar Expert Posts: 29 ✭
    #5
    Re: Question About Solar Amps Being Displayed
    BB. wrote: »
    Also, what is your charging voltage set at? The meter was displaying around 13.9 volts and the battery Green LED was flashing--which appears to indicate that the battery is nearly fully charged (and in PWM mode--basically, throttling the current back to maintain the battery voltage at Float~13.7 volts or Bulk/Absorb around 14.4 volts for flooded cell batteries).

    I would double check the battery type settings--I would expect 14.4 volts if it was charging (and in PWM mode), or 13.7 if it was in float. 13.9 is a bit in between. :confused:

    It seems to stop charging somewhere around 14.0, as before I understood what was going on, the Solar Amps displayed 0.0, and I believe the light was solid green (not blinking), but I'll try to confirm all this tomorrow. I know with my old charge controller as well, the battery got up to about 14v before the controller placed it in float mode.

    The battery is about 4-5ft from the charge controller laying on the shed floor, and the wires are 12AWG.

    So I just need to figure out what fuse to get, how I should hook it up and I'll be set :)
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  • mikeo
    mikeo Solar Expert Posts: 386 ✭✭✭
    #6
    Re: Question About Solar Amps Being Displayed
    So I just need to figure out what fuse to get, how I should hook it up and I'll be set :)
    This would work for your situation and very cheap:
    http://cgi.ebay.com/REAL-8-GAUGE-MAXi-FUSE-HOLDER-50-AMP-WATER-PROOF-USA-/200502265172?pt=LH_DefaultDomain_0
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  • solartechtown.com
    solartechtown.com Solar Expert Posts: 29 ✭
    #7
    Re: Question About Solar Amps Being Displayed
    mikeo wrote: »
    This would work for your situation and very cheap:
    http://cgi.ebay.com/REAL-8-GAUGE-MAXi-FUSE-HOLDER-50-AMP-WATER-PROOF-USA-/200502265172?pt=LH_DefaultDomain_0

    Wow, nice really cheap, might buy 2 :)

    Could you quickly state what the fuse prevents in this setup?

    Like what could happen without the use of a fuse?

    Thanks
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  • mikeo
    mikeo Solar Expert Posts: 386 ✭✭✭
    #8
    Re: Question About Solar Amps Being Displayed
    Could you quickly state what the fuse prevents in this setup?
    The fuse is to protect your wiring. A shorted battery can momentarily source 10000 amps or more, can we say arc welder. Much better to blow a 50 amp fuse then risk a serious burn or house fire. The fuse should be matched to or less then your wire ratings. A #12 copper wire is rated at 20 amps, #10 at 30 amps and so on. I think your inverter at full power draws around 22 amps so #12 wire is too small for your inverter so I recommend #8 wire and 40-50 amp fuse for your 300 watt inverter.
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  • solartechtown.com
    solartechtown.com Solar Expert Posts: 29 ✭
    #9
    Re: Question About Solar Amps Being Displayed
    mikeo wrote: »
    The fuse is to protect your wiring. A shorted battery can momentarily source 10000 amps or more, can we say arc welder. Much better to blow a 50 amp fuse then risk a serious burn or house fire. The fuse should be matched to or less then your wire ratings. A #12 copper wire is rated at 20 amps, #10 at 30 amps and so on. I think your inverter at full power draws around 22 amps so #12 wire is too small for your inverter so I recommend #8 wire and 40-50 amp fuse for your 300 watt inverter.

    Thanks for the info mikeo.

    Two questions, as I just received the fuse in the mail today.

    1. Which wire should I place the fuse on, the positive or negative. I'm assuming the positive: Inverter positive wire > Fuse > battery positive terminal

    2. Is there a right/wrong way to putting the fuse in the fuse holder? Like it fits either way I turn it, and I'm not sure if fuses have polarities like a LED does for example...

    Thanks! :D
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  • mikeo
    mikeo Solar Expert Posts: 386 ✭✭✭
    #10
    Re: Question About Solar Amps Being Displayed
    1. Which wire should I place the fuse on, the positive or negative. I'm assuming the positive: Inverter positive wire > Fuse > battery positive terminal

    2. Is there a right/wrong way to putting the fuse in the fuse holder? Like it fits either way I turn it, and I'm not sure if fuses have polarities like a LED does for example...
    put the fuse on the positive terminal, and there is no polarity on which way the fuse is plugged into the fuse holder
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